Cardiovascular disease is the most common cause of death in the western world. Diagnostic imaging of the heart through ultrasound imaging (US) and nuclear imaging (SPECT) is a valuable tool for assessing the extent of cardiac disease. Although both US and SPECT are effective modalities and are widely used, they each have limitations, and improving their effectiveness is an important goal of biomedical imaging research. Image registration techniques have been recently developed for multimodality images of various parts of the body. Since US and SPECT images provide complementary information of the heart (anatomy and function), one expects that viewing registered images would improve diagnostic efficacy. Although some cardiac image registration research has been done for other modalities, very little work has been published for US and SPECT together. In Phase I, we plan to demonstrate the feasibility of our innovative approach to US and SPECT cardiac image registration, using an automated mutual information algorithm. We will test the accuracy of the registration methods using existing clinical data, and expert clinicians will evaluate the quality of the registration. This research will lead to software tools that will improve diagnostic accuracy of cardiac imaging at minimal cost. PROPOSED COMMERCIAL APPLICATIONS: This research will lead to commercially-available software for cardiac image registration. By using standard acquisition protocols and standard file formats, we will be able to offer this software as a service to echocardiologists and nuclear cardiologists. We plan to commercialize the software on a subscription or fee-for-use basis. The existing market is rather large (over $2 billion for cardiac ultrasound and SPECT imaging), and thus even minimal market penetration will lead to commercial success.